<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>display</title>
</head>
<body>
    <style>
       body{
        background-image: url(./背景7.jpg);
        background-size: 100%;
       }
    .nb{
        text-align: center;
        display: inline-block;
        border-radius: 50%;
        margin: 1px;
        width: 100px;
        height: 100px;
        line-height: 100px;
        font-size: 25px;
        border:  2px #bbb4b4 solid;
        color: white;
    }
    .nb:nth-child(2n+1){
        background-color: blue;
    }
    .nb:nth-child(2n){
        background-color: red;
    }
    </style>
    <div>
        <span class="nb">1</span>
        <span class="nb">2</span>
        <span class="nb">3</span>
        <span class="nb">4</span>
        <span class="nb">5</span>
        <span class="nb">6</span>
        <span class="nb">7</span>
        <span class="nb">8</span>
        <span class="nb">9</span>
        <span class="nb">10</span>
        <span class="nb">11</span>
        <span class="nb">12</span>
        <span class="nb">13</span>
        <span class="nb">14</span>
        <span class="nb">15</span>
        <span class="nb">16</span>
        <span class="nb">17</span>
        <span class="nb">18</span>
        <span class="nb">19</span>
        <span class="nb">20</span>
        <span class="nb">21</span>
        <span class="nb">22</span>
        <span class="nb">23</span>
        <span class="nb">24</span>
        <span class="nb">25</span>
        <span class="nb">26</span>
        <span class="nb">27</span>
        <span class="nb">28</span>
        <span class="nb">29</span>
        <span class="nb">30</span>
        <span class="nb">31</span>
        <span class="nb">32</span>
        <span class="nb">33</span>
        <span class="nb">34</span>
        <span class="nb">35</span>
        <span class="nb">36</span>
        <span class="nb">37</span>
        <span class="nb">38</span>
        <span class="nb">39</span>
        <span class="nb">40</span>
        <span class="nb">41</span>
        <span class="nb">42</span>
        <span class="nb">43</span>
        <span class="nb">44</span>
        <span class="nb">45</span>
        <span class="nb">46</span>
        <span class="nb">47</span>
        <span class="nb">48</span>
        <span class="nb">49</span>
        <span class="nb">50</span>
        <span class="nb">51</span>
        <span class="nb">52</span>
        <span class="nb">53</span>
        <span class="nb">54</span>
        <span class="nb">55</span>
        <span class="nb">56</span>
        <span class="nb">57</span>
        <span class="nb">58</span>
        <span class="nb">59</span>
        <span class="nb">60</span>
        <span class="nb">61</span>
        <span class="nb">62</span>
        <span class="nb">63</span>
        <span class="nb">64</span>
        <span class="nb">65</span>
        <span class="nb">66</span>
        <span class="nb">67</span>
        <span class="nb">68</span>
        <span class="nb">69</span>
        <span class="nb">70</span>
        <span class="nb">71</span>
        <span class="nb">72</span>
        <span class="nb">73</span>
        <span class="nb">74</span>
        <span class="nb">75</span>
        <span class="nb">76</span>
        <span class="nb">77</span>
        <span class="nb">78</span>
        <span class="nb">79</span>
        <span class="nb">80</span>
        <span class="nb">81</span>
        <span class="nb">82</span>
        <span class="nb">83</span>
        <span class="nb">84</span>
        <span class="nb">85</span>
        <span class="nb">86</span>
        <span class="nb">87</span>
        <span class="nb">88</span>
        <span class="nb">89</span>
        <span class="nb">90</span>
        <span class="nb">91</span>
        <span class="nb">92</span>
        <span class="nb">93</span>
        <span class="nb">94</span>
        <span class="nb">95</span>
        <span class="nb">96</span>
        <span class="nb">97</span>
        <span class="nb">98</span>
        <span class="nb">99</span>
        <span class="nb">100</span>

    </div>
</body>
</html>